The present invention relates to a magnetic disk drive and, particularly, to a magnetic disk drive in which a recording and reproducing operation is performed while a magnetic head of the magnetic disk drive is made in contact with a magnetic disk and a method of manufacturing the magnetic disk drive.
The recording density of magnetic disks in a magnetic disk drive used as an external memory for such as a computer system has been increased at high rate. As a result, the flying height of a magnetic head becomes smaller and smaller and, recently, it becomes as small as 0.1 .mu.m or less. It is expected that, in the near future, a contact recording system, in which magnetic heads perform a recording and reproducing operation while they are always in contact with magnetic disks, shall be used.
Each of U.S. Pat. No. 5,041,932 (referred to as article 1) and Japanese Patent Application Laid-open No. H5-114116 (referred to as article 2) discloses a magnetic head structure suitable for such contact recording and reproducing system and a method of manufacturing the magnetic head structure. In these articles, a technique for recording and reproducing information is disclosed in which a small contact pad having a magnetic recording/reproducing pole portion embedded therein is in sliding contact with the magnetic disk.
A problem inherent to the contact recording and reproducing system is an abrasion of the magnetic head and/or the magnetic disk due to the sliding contact therebetween. However, this problem has become practically negligible for the magnetic disk drive by a use of a carbon material in the contact pad portion and/or a protective layer on the magnetic disk, a reduction of weight of the magnetic head, a reduction of load of the head and an employment of a perpendicular magnetic recording system, etc.
In the perpendicular magnetic recording system, it has been known that a recording and reproducing characteristics of the system varies with a minute variation of contacting state between the magnetic head, particularly, the pole portion, and the magnetic disk. For example, in the above mentioned contact recording and reproducing system, a slight roll angle of the magnetic head with respect to the magnetic disk affects the recording and reproducing characteristics considerably and, in some case, there may be a case where a desired recording and reproducing characteristics can not be obtained. As described in "IEEE Transactions on Magnetics", Vol. 27, No. 6, Page 4923, November 1991 (referred to as article 3), in order to guarantee a reliable contact between a magnetic head and a magnetic disk, that is, to obtain a desired recording and reproducing characteristics of a magnetic disk drive, a preliminary operation is required to preliminarily abrade the magnetic head prior to a normal recording and reproducing operation. As mentioned previously, however, the preliminary operation takes a long time since the magnetic head and magnetic disk system is designed such that an abrasion is restricted to suitable a low level.
Although the article 3 mentions the necessity of preliminary smoothing operation, that is, an initial head abrasion, in order to ensure the contact of the contact head and the magnetic disk, it does not disclose any concrete mean for performing the same. The article 1 is completely silent on the preliminary smoothing operation.